Image processing apparatus, image processing method, and non-transitory computer-readable storage medium

Abstract

An image processing apparatus includes circuitry. The circuitry irreversibly compresses an input image to generate an irreversibly compressed image. The circuitry decompresses the irreversibly compressed image to generate a decompressed image. The circuitry corrects a surround of a target area in the decompressed image to generate a corrected image. The target area corresponds to a line drawing image included in the input image. The circuitry generates first to third image layers from the corrected image. The first image layer is a binary image including a line drawing alone. The second image layer includes a line drawing area. The third image layer includes a background area. The circuitry reversibly compresses the first image layer and irreversibly compress the second and third image layers. The circuitry generates an output file based on the first to third image layers compressed.

What is claimed is: 
     
       1. An image processing apparatus, comprising:
 circuitry configured to:
 irreversibly compress an input image to generate an irreversibly compressed image; 
 decompress the irreversibly compressed image to generate a decompressed image; 
 correct a surrounding of a target area in the decompressed image to generate a corrected image, the target area corresponding to a line drawing image included in the input image; 
 generate a first image layer, a second image layer and a third image layer from the corrected image, the first image layer being a binary image that contains a line drawing, the second image layer includes a line drawing area, and the third image layer includes a background area; 
 reversibly compress the first image layer to generate a reversibly compressed first image layer; 
 irreversibly compress the second image layer to generate an irreversibly compressed second image layer; 
 irreversibly compress the third image layer to generate an irreversibly compressed third image layer; and 
 generate an output file based on the reversibly compressed first image layer, the irreversibly compressed second image layer, and the irreversibly compressed third image layer. 
 
 
     
     
       2. The image processing apparatus according to  claim 1 , wherein the circuitry is further configured to:
 detect the line drawing image from the input image; 
 reversibly compress the line drawing image to generate a reversibly compressed image; 
 decompress the reversibly compressed image to generate a decompressed line drawing image; and 
 specify the target area based on the decompressed line drawing image. 
 
     
     
       3. The image processing apparatus according to  claim 2 , wherein the circuitry is further configured to correct the target area in the decompressed image with the decompressed line drawing image. 
     
     
       4. The image processing apparatus according to  claim 2 , wherein the circuitry is further configured to:
 determine image type information indicating a type of the input image based on the decompressed image; and 
 correct the surrounding of the target area in the decompressed image with the decompressed line drawing image and the image type information to generate the corrected image. 
 
     
     
       5. The image processing apparatus according to  claim 1 , wherein the circuitry is further configured to:
 detect a line drawing image area corresponding to the line drawing image from the decompressed image; and 
 correct, with the decompressed image, a second surrounding of the line drawing image area based on an area set according to characteristics of the input image with respect to the line drawing image area, to generate the corrected image. 
 
     
     
       6. The image processing apparatus according to  claim 1 , wherein the circuitry is configured to replace pixels around the target area with single-color pixels. 
     
     
       7. The image processing apparatus according to  claim 1 , wherein in response to the decompressed image including a given percentage or more of white pixels, the circuitry is configured to replace a pixel in an area other than the line drawing image in the decompressed image with a white pixel. 
     
     
       8. The image processing apparatus according to  claim 1 , wherein the circuitry is further configured to:
 detect an edge of the line drawing; and 
 enhance the edge of the line drawing to generate an edge-enhanced image. 
 
     
     
       9. The image processing apparatus according to  claim 8 , wherein the circuitry is further configured to:
 binarize the edge-enhanced image to acquire the binary image; and 
 extract a low-brightness object from the binary image, the low-brightness object being distinguishable from the background area. 
 
     
     
       10. An image processing method, comprising:
 irreversibly compressing an input image to generate an irreversibly compressed image; 
 decompressing the irreversibly compressed image to generate a decompressed image; 
 correcting a surrounding of a target area in the decompressed image to generate a corrected image, the target area corresponding to a line drawing image included in the input image; 
 generating a first image layer, a second image layer and a third image layer from the corrected image, the first image layer being a binary image that contains a line drawing, the second image layer includes a line drawing area, and the third image layer includes a background area; 
 reversibly compressing the first image layer to generate a reversibly compressed first image layer; 
 irreversibly compressing the second image layer to generate an irreversibly compressed second image layer; 
 irreversibly compressing the third image layer to generate an irreversibly compressed third image layer; and 
 generating an output file based on the reversibly compressed first image layer, the irreversibly compressed second image layer, and the irreversibly compressed third image layer. 
 
     
     
       11. The image processing method according to  claim 10 , further comprising:
 detecting the line drawing image from the input image; 
 reversibly compressing the line drawing image to generate a reversibly compressed image; 
 decompressing the reversibly compressed image to generate a decompressed line drawing image; and 
 specifying the target area based on the decompressed line drawing image. 
 
     
     
       12. The image processing method according to  claim 11 , further comprising correcting the target area in the decompressed image with the decompressed line drawing image. 
     
     
       13. The image processing method according to  claim 11 , further comprising:
 determining image type information indicating a type of the input image based on the decompressed image; and 
 correcting the surrounding of the target area in the decompressed image with the decompressed line drawing image and the image type information to generate the corrected image. 
 
     
     
       14. The image processing method according to  claim 10 , further comprising:
 detecting a line drawing image area corresponding to the line drawing image from the decompressed image; and 
 correcting, with the decompressed image, a second surrounding of the line drawing image area based on an area set according to characteristics of the input image with respect to the line drawing image area, to generate the corrected image. 
 
     
     
       15. The image processing method according to  claim 10 , further comprising replacing pixels around the target area with single-color pixels. 
     
     
       16. The image processing method according to  claim 10 , further comprising:
 replacing, in response to the decompressed image including a given percentage or more of white pixels, a pixel in an area other than the line drawing image in the decompressed image with a white pixel. 
 
     
     
       17. The image processing method according to  claim 10 , further comprising:
 detecting an edge of the line drawing; and 
 enhancing the edge of the line drawing to generate an edge-enhanced image. 
 
     
     
       18. The image processing method according to  claim 17 , further comprising:
 binarizing the edge-enhanced image to acquire the binary image; and 
 extracting a low-brightness object from the binary image, the low-brightness object being distinguishable from the background area. 
 
     
     
       19. A non-transitory, computer-readable storage medium storing computer-readable program code that causes a computer to perform an image processing method, the image processing method comprising:
 irreversibly compressing an input image to generate an irreversibly compressed image; 
 decompressing the irreversibly compressed image to generate a decompressed image; 
 correcting a surrounding of a target area in the decompressed image to generate a corrected image, the target area corresponding to a line drawing image included in the input image; 
 generating a first image layer, a second image layer and a third image layer from the corrected image, the first image layer being a binary image that contains a line drawing, the second image layer includes a line drawing area, and the third image layer includes a background area; 
 reversibly compressing the first image layer to generate a reversibly compressed first image layer; 
 irreversibly compressing the second image layer to generate an irreversibly compressed second image layer; 
 irreversibly compressing the third image layer to generate an irreversibly compressed third image layer; and 
 generating an output file based on the reversibly compressed first image layer, the irreversibly compressed second image layer, and the irreversibly compressed third image layer.